I guess Zoro cannot be the WSS as well because he also used kicks and his arms in fights
Zoro has more instances of not using his swords in fights than Ray, and yet he is going to be the WSS. Or maybe Zoro won't be the WSS? Or are you saying that Zoro will be the wss, but there will be people who use swords and are stronger than him?
Too many assumptions here, firstly with the WSS title existing in their era, then who would have it. Unsubstantiated claims as well.
Databooks said that Mihawk and Vista have similar level of swordsmanship but Vista could not compete with Mihawk, meaning that it is not the swordsmanship that plays the only role in it. Fujitora, a df user, was called a blind swordsman, meaning that even using a df does not disqualify one from being a swordsman, Shiryu the same, Kinemon was introduced as a samurai, meaning swordsman. Kuina, whose dream was to be the wss herself stated that her body is too weak, meaning that even if she were more skillful than Mihawk she would not be stronger. Finally, Mihawk's title is the world's strongest swordsman, not the world's most proficient sword user or the sort. The official translator had this to say when being questioned about what the term kenshi (swordsman) means
Kinemon can cut fire, Zoro cannot. Thus Kinemon has more skill than Zoro. Zoro fights Kinemon. Guess who wins. Hint: It is Zoro. So a more skilled df using swordsman loses against a stronger less skilled non df using swordsman. Is Kinemon a better candidate for the WSS than Zoro? I'd say no.